Top Coat over Zinsser Amber Shellac - antique grandfather clock

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Forum topic by Kent posted 11-24-2018 04:04 PM 1580 views 0 times favorited 5 replies Add to Favorites Watch
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49 posts in 5126 days

11-24-2018 04:04 PM

Topic tags/keywords: question top coat shellac finishing

Hello, it feels good to be back after a few years of not logging in. I hoping I can receive some direction on what to use as the top coat.

I was not sure what finish this 100 year old clock had, but the old varnish was flaking. I applied a stripper and 000 steel wool for a day with lacquer thinner which seemed to work well. I still don’t know what was on it before. It ended up feeling waxy.

I took a chance and applied two coats of un-thinned liquid Zinsser Amber. It came out great. I thought I would be done. However, the grain on what looks to be oak, (the sides are veneer) needs to be filled, as there are thin crevices in the grain pretty much all over it.

I read quite a bit on here and other online sources and there are differences of opinion on what can be applied over shellac.

I still don’t understand what dewaxed shellac is and whether Zinsser Amber shellac is dewaxed. Does dewaxed only mean to dull the finish with steel wool or sandpaper ?

Some say any finish will work over shellac – poly or non poly.

Others suggest Arm-R-Seal Oil & Urethane.

Zinsser Seal Coat is recommended by many but it is designed as a pre-finish sealer so I am confused about that.

I am looking for a satin or semi gloss finish that will fill the grain and work over the amber shellac. Being a clock, it does not need a lot of protection except from the sun through a window.

Thank you.


5 replies so far

View bondogaposis's profile


6069 posts in 3642 days

#1 posted 11-24-2018 04:29 PM

Zinsser amber shellac is not de-waxed, you are going to have adhesion problems if you try to put anything over it.

-- Bondo Gaposis

View Fred Hargis's profile

Fred Hargis

7302 posts in 3784 days

#2 posted 11-24-2018 04:51 PM

The adhesion problems with shellac occur with anything that uses urethane/polyurethane resins and some waterbiorne finishes, the problem isn’t with the shellac…it’s the urethane. Putting them on top of something like shellac that hasn’t been dewaxed may cause problems, though that’s not absolute. So the mixed messages you see are because some have had success, but likely most have not. Like Bondo said, the Amber is not dewaxed. The Seal Coat is, however. If you want to apply varnish over the Amber shellac, you could use an alkyd resin varnish like Pratt and Lambert 38 or SW Fast Dry Oil Varnish. One other thing, some will tell you to top coat the Amber with some Seal Coat and go ahead with whatever you do. Well, that might work…but shellac will melt into itself, the new coat dissolves and mixes with the previous coats. So there is some risk in doing that as well. It’s another one of those things that some have had success with and others haven’t.

-- Our village hasn't lost it's idiot, he was elected to congress.

View OSU55's profile


2906 posts in 3280 days

#3 posted 11-24-2018 05:56 PM

The nonpoly varnishes are an option, and since its a clock that wont be handled lacquer is another option . Never tried the brushing lacquer but spraying it is easy. Another option is to continue with the shellac. You could french polish the shellac and it will fill the grain. It would need to be rubbed back in gloss with 0000 steel wool or equivalent. French polish takes time but so will any finish to eventually fill the grain.

You might try just adding a couple of coats of shellac and rubbing it back in gloss without fully filling the grain to see if that suits you. I have also had success with sanding a coat of shellac with ~600, let the shellac dust fill the grain, then recoating. Shellac burns in (remelts) the dust into a contiguous coat. Another possibility is to mix a little oil based dye with wax and fill the grain with wax – can be problematic in the long term.

View Kent's profile


49 posts in 5126 days

#4 posted 11-24-2018 08:42 PM

Thank you very much.

View Kent's profile


49 posts in 5126 days

#5 posted 11-24-2018 09:31 PM

I think I will go w another coat or two of shellac w 0000 between coats.

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